This invention relates to golf clubs and, more particularly, to a golf club whose clubhead has a sole with a contour, extending from the clubface towards the rear of the clubhead, having both convex and concave portions.
In the art of sole designs for both golf club "woods" and "irons" it is known to provide a sole with a convex camber from heel to toe. A typical value for the radius of the camber is approximately 5-9 inches. The advantage of a cambered sole is that it significantly reduces the amount of sole material that comes in contact with the ground, as compared to a sole that is flat from heel to toe. The cambered sole provides for less resistance of the clubhead to ground drag as the club contacts the ground. It also allows the golfer to keep the clubhead as low to the ground as possible for variations in golf club lie positions (e.g., uphill or downhill lies).
It is also known in the art of sole designs for both types of golf clubs, especially irons, to provide a sole having a convex camber extending from the front striking face toward the rear of the clubhead. That is, the camber is provided along the "width" of the sole. The sole width is defined as the distance from the leading edge of the clubface to the farthest rear portion of the sole, as measured along the ground line. Such convex camber reduces the effective sole width of the club, which has the further benefit of reducing the amount of "turf dig" on the leading edge of the club.
It is known in the art that the narrower the width of the sole, the less the leading edge of the club will raise up off the ground when the golfer rolls the face open (i.e., less "bounce"). "Bounce" is an anti-sole digging feature designed in on some clubs. Bounce is defined to be the angle that the sole makes with the ground line when the front leading edge of the clubhead is higher off the ground than the rear trailing edge of the clubhead. Thus, bounce can be increased by either designing in an increased sole angle, or the golfer can "roll the clubface open" more on a club having a relatively large sole width. In this latter situation, the greater the sole width the more the bounce. However, a smaller amount of bounce lessens the chance that the golfer will "blade" or "scull" the ball (i.e., hit the ball thin) when hitting the ball off the grass. Normally, "bounce" is purposely designed into sand wedges to keep the clubhead from digging deeply into the sand.
It is also known to provide a sand wedge with a sole design that is concave for a large portion of the sole from the front of the clubface to the rear of the clubhead. See, for example, U.S. Pat. No. 3,810,631 to Braly. The patentee therein believes that the sole design of the sand wedge can be used to more easily propel a golfball along a path of desired trajectory and distance. This is due to the improved dynamic stability of the head of the club in the medium (i.e., sand) upon which the ball rests, and because of the minimization of the rate of deceleration of the speed of the clubhead upon entry into and passage through the sand.
Further, it is known to provide a golf club with a complex sole that is both concave and convex in various planes through the sole. See, for example, U.S. Pat. No. 4,850,593 to Nelson. The stated purpose of such design is to improve the aerodynamic performance of the club.
Also, it is known to position the clubhead's center of gravity equal to or lower than the golfball's center of gravity. This increases the likelihood that the resulting golf shot will impart a proper trajectory to the ball and a more solid "feel" to the golfer. To accomplish this positioning of the center of gravity, the mass of the clubhead is distributed farther rearward and placed low to the ground. However, this adds to the amount of sole width on the club, which has all of the attendant problems described hereinbefore, along with the further problem of potentially causing greater interference with the turf by the rear of the clubhead, or better known as "sole slap".
However, heretofore, no known clubhead design has been provided for all the clubs within a set of golf clubs, including woods, irons and putter, that has a sole with a convex portion extending from the front leading edge of the clubface toward the rear of the clubhead, followed by a concave portion extending to the rear of the clubhead.
Accordingly, it is a primary object of the present invention to provide a golf club with a head having a sole that is shaped to reduce the possibility of interference of the sole with the turf by both the leading edge and trailing portion of the clubhead.
It is a general object of the present invention to provide a golf club head with a sole that is relatively more efficient in getting the ball in the air.
It is a further object of the present invention to provide a golf club head with a sole that allows more of the weight of the clubhead to be located in the rear of the clubhead so as to properly position the center of gravity of the clubhead with respect to a golfball.
It is a still further object of the present invention to provide a golf club head with a sole that does not cause the clubface to "roll in" while a golfer addresses the ball.
It is yet another object of the present invention to provide a golf club head with a sole that allows a golfer to lay the clubhead more open, if desired, to effectively produce a greater loft angle of the clubface without a corresponding relatively large increase in the bounce of the club.
The above and other objects and advantages of this invention will become more readily apparent when the following description is read in conjunction with the accompanying drawings.